e brown trout Salmo trutta m. fario L. from lake Mały Staw (Giant Mts., SW Poland) a biological and parasitological survey

WITKOWSKI A., POPIOLEK M., BłACHUTA J., KUSZNIERZ J. & KOTUSZ J. 2008: e brown trout Salmo trutta m. fario L. from lake Mały Staw (Giant Mts., SW Poland) a biological and parasitological survey. Opera Corcontica 45: 151 161. e brown trout Salmo trutta m. fario L. from lake Mały Staw (Giant Mts., SW Poland) a biological and parasitological survey Pstrąg potokowy Salmo trutta m. fario L. z Małego Stawu (Karkonosze, południowo-zachodnia Polska) badania biologiczne i parazytologiczne Andrzej Witkowski 1, Marcin Popiołek 2, Jan Błachuta 3, Jan Kusznierz 4 & Jan Kotusz 1 1 Wrocław University, Museum of Natural History, Sienkiewicza 21, 50-335 Wrocław, PL, a.witkowski@biol.uni.wroc.pl; kotusz@biol.uni.wroc.pl 2 Wrocław University of Environmental and Life Sciences, Department of Zoology & Ecology, Kożuchowska 5b, 51-631 Wrocław, PL, popiolek@ozi.ar.wroc.pl 3 Institute of Meteorology and Water Management, Wrocław Branch, Parkowa 30, 51-616 Wrocław, PL, blachuta@biol.uni.wroc.pl 4 Wrocław University, Zoological Institute, Department of Biology & Vertebrate Protection, Sienkiewicza 21, 50-335 Wrocław, PL, kusznierz@biol.uni.wroc.pl An ichthyological survey carried out in 2004 2005 in the Karkonosze National Park included lakes and streams. Forty five individuals of the brown trout (Salmo trutta m. fario L.) were caught in three periods in the lake Mały Staw. e material provided the basis to estimate the growth rate, fecundity, food basis and parasite fauna of the fish. e growth of brown trout in the montane, oligotrophic lake is moderate while the condition and fecundity are very low, as a result of the scanty food resources of the lake. e population to a large extent feeds on allochthonous organisms. Its parasite fauna is represented by two species only Crepidostomum farionis (Digenea) and Neoechinorhynchus rutili (Acanthocephala), which show a high prevalence and intensity of infection. W latach 2004 2005 na terenie Karkonoskiego Parku Narodowego przeprowadzono badania ichtiologiczne, którymi objęto potoki i jeziora. W Małym Stawie w trzech okresach odłowiono 45 pstrągów potokowych (Salmo trutta m. fario L.). Materiały te posłużyły do oceny tempa wzrostu, płodności, pokarmu oraz ich parazytofauny. Pstrąg potokowy w tym górskim, oligotroficznym, jeziorze rośnie przeciętnie, a jego kondycja oraz płodność są bardzo niskie. Wynika to z ubogiej bazy pokarmowej tego akwenu. Gatunek ten odżywia się tam w dużej mierze allochtoniczymi organizmami. Jego parazytofauna reprezentowana jest tylko przez dwa gatunki (Digenea i Acanthocephala), które wykazują bardzo wysoką prewalencję i intensywność zarażenia. 151

Keywords: Giant Mts., oligotrophic lake, growth, food, fecundity, parasites Słowa kluczowe: Karkonosze, jezioro oligotroficzne, wzrost, pokarm, płodność, pasożyty INTRODUCTION In the Polish part of the Giant Mts., the brown trout (S. trutta m. fario) inhabits most streams and only one of the two lakes Mały Staw (Fig. 1) (WITKOWSKI & JABłOńSKI 1985). It is the highest situated locality (1183 m a.s.l.; N 50 o 44 55, E 15 o 42 03 ) of the species in the Sudetes. e lake is 2.88 ha in area, its maximum depth is 7.3 m, and the water volume 99 925 m 3 (KOMAR 1985). e brown trout has been known to occur in Mały Staw in the Karkonosze National Park (KNP) for a long time (SCHWENCKFELD 1603, GLOGER 1833, PAX 1925), though its origin is unclear. According to some authors it has been introduced there, others believe it is an autochthonous locality. e latter is supported by the fact that the trout is abundant in the Łomnica stream flowing out of the lake (A. Witkowski unpubl. data) and this was probably the route through which it invaded Mały Staw. Contrary to the Polish part of the Tatras (GLIWICZ 1963, JARA & MARKIEWICZ 1968, JARA et al. 1972, RO- KICKI et al. 1998, ŚLUSARSKI 1958 a, b, c, ŻARNECKI & BIENIARZ 1967) there was no detailed information on the biology of the high- -mountain trout population from the Giant Mts. e fact prompted us to study the age structure, growth, food, fecundity and parasite fauna of the population from this oligotrophic lake. MATERIAL AND METHODS Fig. 1. Mały Staw lake in the Polish part of the Giant Mts. (photo A. Raj) Ryc. 1. Mały Staw w polskiej części Karkonoszy (fot. A. Raj) e material was collected on three occasions: 16 Nov 2004, 17 Jun 2005 and 31 Aug 2005. e trout was caught with gill nets (mesh size 15 30 mm) and fishing rods (spinning). Because the lake is located in the strict nature reserve within the KNP the number of individuals caught was limited to the necessary minimum. A total of 45 specimens were caught, 29 on the first occasion, eight on the second and third each. e specimens were preserved in 4% formalin, and examined in detail in the laboratory. e total length (Tl) and body length (Sl) were measured to the nearest 1 mm; the fish were weighted to the nearest 1 g. Scales for age and growth rate assessment were taken anterior to the dorsal fin, below the lateral line. e age and growth assessment was based on 30 specimens; 15 specimens had regenerated scales which were impossible to read. e scales were photographed with a digital camera coupled with a microscope; the number and position of annual rings were 152

then estimated and the scales measured along the oral radius. R. Lea s method of back readings was applied to estimate the growth, using the equation Tln = s n /s x Tl, where Tln reconstructed total length of the fish in the nth year of life; s n length of scale radius in the nth year of life; Tl total length of the fish at the moment of catch; s total length of the scale radius. e age structure estimates were based on direct age readings at the moment of catch. e current year of life was denoted with symbols 2 + to 6 +. In the case of back readings the size reached a er completing subsequent years of life was denoted with symbols: I to VI. Condition coefficient (K) was calculated with Fulton s formula K = w x 100/ Tl 3, where: w mass in g, and Tl total length in cm. e female fecundity was estimated by counting all eggs in the right and le part of the ovary. Only the individuals caught in the autumn (November 2004: n = 9) were examined, since in the summer (June-August 2005) males prevailed in the catches, and the few females had poorly developed gonads. Food composition was ascertained by means of analysing the contents of oesophagus and stomach in 41 specimens. e food items were identified down to the family or genus level, only exceptionally species was determined. Identification keys to aquatic invertebrate taxa were used (KOłODZIEJCZYK & KOPERSKI 2000, ROZKOšNÝ 1980). e proportion of particular taxa in the food was expressed as percent of number of total taxa. Specimens preserved in 4% formalin were subjected to parasitological examination. Following a few hours rinsing in tap water, standard parasitological dissection was carried out, including stomach, duodenum, intestine, liver, spleen, gonads, swim bladder and body cavity. e parasites were rinsed, counted and preserved in 70% ethyl alcohol. Fixed Digenea were stained with borax carmin, contrasted, dehydrated, and a er clearing closed with Canada balsam on microscope slides. e same procedure was applied to Acanthocephala, except that they were not stained. e parasites were identified using MORAVEC (2004) key, formulas of the basic parasitological indices followed POJMAńSKA (1993). RESULTS AGE AND GROWTH In the sample from Mały Staw (n = 45) age classes from 2 + to 6 + years were represented. eir proportions were following: 2 + - 3.3%; 3 + - 10.0%; 4 + - 26.6%; 5 + - 56.6%; 6 + - 3.3%. Catches with the use of selective equipment (rods and gill nets) do not reflect the actual population structure, but it can be conjectured that in all likelihood individuals aged 4 + and 5 + constitute most of the population, and the maximum age attained was 7 years. e growth of the brown trout from Mały Staw is presented in Tab. 1 and Fig. 2. Fig. 2. Growth of the brown trout (S. trutta m. fario) in Mały Staw Ryc. 2. Tempo wzrostu pstrąga potokowego (S. trutta m. fario) w Małym Stawie 153

Tab. 1. Growth (in mm Tl) of the brown trout (S. trutta m. fario) in Mały Staw Wzrost (w mm Tl) pstrąga potokowego (S. trutta m. fario) w Małym Stawie Age wiek I II III IV V VI Mean średnia 83.8 143.0 180.3 229.0 270.9 293.0 Range zakres 70 92 130 155 169 188 219 243 240 290 SD 1.128 1.349 1.115 1.482 3.286 SE 6.234 7.388 6.006 7.557 13.941 CONDITION COEFFICIENT e values of condition coefficient in the brown trout from Mały Staw were very low and rarely exceeded 1 (Tab. 2). In all periods they were somewhat higher in females compared to males. In both sexes the lowest values were recorded in the late autumn, i.e. a er most individuals had spawned. e highest values (especially in females) were noted at the end of summer (August). Tab. 2. Condition coefficient (K) of the brown trout (S. trutta m. fario) from Mały Staw (f females, m males) Współczynnik kondycji (K) pstrąga potokowego (S. trutta m. fario) z Małego Stawu (f samice, m samce) 16 Nov 2004 17 Jun 2005 31 Aug 2005 f (n=19) m (n=11) f (n=3) m (n=5) f (n=4) m (n=4) 0.855 0.771 0.922 0.902 1.071 0.958 0.684 1.100 0.464 1.023 0.777 1.111 0.889 1.023 1.044 1.126 0.806 0.981 FECUNDITY e fecundity of the trout was low and ranged from 310 to 782 eggs (mean 451, S.D. 168.6). e dependence between the female size and fecundity is presented in Fig. 3. Fig. 3. Dependence between length (Tl in mm) and fecundity of the brown trout (S. trutta m. fario) from Mały Staw Ryc. 3. Zależność miedzy rozmiarami (Tl w mm) a płodnością pstrąga potokowego (S. trutta m. fario) z Małego Stawu 154

Tab. 3. Food composition of the brown trout (S. trutta m. fario) from Mały Staw Skład pokarmu pstrąga potokowego (S. trutta m. fario) z Małego Stawu Date 16 Nov 2004 17 Jun 2005 31 Aug 2005 Fish number 29 9 9 Fish with empty stomach 4 1 1 Taxon N %N F N %N F N %N F Leptoceridae l 3 0.30 12.5 Mallonidae l 1 0.04 4.0 Plectrocnemia sp. l 48 1.99 36.0 1 0.13 12.5 Potamphlax sp. l 1 0.04 4.0 Sericostoma sp. l 1 0.04 4.0 Trichoptera i n.det. 1 0.04 4.0 1 0.13 12.5 Baetidae l 8 0.81 12.5 Siphlonuridae l 2 0.20 12.5 Isoperla sp. l 1 0.13 12.5 Nemouridae l 3 0.12 8.0 1 0.13 12.5 Sialis lutaria l 14 0.58 32.0 4 0.53 50.0 3 0.30 25.0 Chironomidae i 1635 67.62 52.0 368 48.36 62.5 Chironomidae p 340 14.08 44.0 3 0.39 12.5 Chironomidae l 322 13.32 68.0 49 6.44 37.5 32 3.25 12.5 Dicranota l 4 0.17 4.0 3 0.39 12.5 Simuliidae i 1 0.13 12.5 Simuliidae l 1 0.13 12.5 Dytiscidae i 3 0.12 12.0 5 0.66 12.5 1 0.10 12.5 Pisidium sp. 12 0.50 4.0 1 0.13 12.5 Hydracarina 1 0.13 12.5 Trout eggs 1 0.04 4.0 Chrysomela decemlinata i 1 0.13 12.5 Chrysomelidae i 25 1.03 8.0 55 7.23 37.5 10 1.01 25.0 Curculionidae i 55 7.23 37.5 20 2.03 37.5 Elateridae i 2 0.08 4.0 94 12.37 75.0 Scarabidae i 4 0.53 25.0 3 0.30 12.5 Scolytidae i 1 0.04 4.0 29 2.94 37.5 Staphylinidae i 29 3.81 50.0 8 0.81 37.5 Formicidae i 823 83.47 100.0 Vespidae i 1 0.10 12.5 Hymenoptera i 1 0.04 4.0 12 1.58 37.5 6 0.61 25.0 Diptera i 1 0.04 4.0 41 5.39 50.0 26 2.64 37.5 Heteroptera i 17 2.23 75.0 9 0.91 62.5 Homoptera i 1 0.04 4.0 13 1.71 37.5 1 0.10 12.5 Arachnidae 1 0.10 12.5 Clethrionomys glareolus 1 0.04 4.0 TOTAL 2418 100.0 761 100.0 986 100.0 Abbreviations: N number of individuals, %N percentage number; F frequency of occurrence (without fish with empty stomach); l larvae; p pupae; i images Objaśnienia: N liczba osobników, %N liczebność w procentach, F frekwencja (bez ryb z pustym żołądkiem); l larwy, p poczwarki, i formy dorosłe 155

FOOD e food of the brown trout in Mały Staw showed great seasonal variation (Tab. 3). In the late autumn (November) the trout consumed mostly Chironomidae (95% of prey items), most of which were pupae and images collected from of near the water surface. Among benthic organisms chironomid larvae were the most numerous (ca. 13%) followed by large larvae of case-less caddisflies Plectronemia sp. (ca. 2%). Terrestrial organisms (allochthonous) constituted slightly over 1% of the diet. e stomach of one fish contained a fish egg, and another fish had a vole (Cleithrionomys glareolus) (body length 81 mm, tail length 42 mm) in its stomach. In the early summer (June) the most common prey items were still chironomids (over 55%), nearly 50% of the being images. Benthic organisms, apart from chironomid larvae (ca. 6%), were few (ca. 2.5%). Allochthonous food terrestrial insects (ca. 42%) formed an important diet component in that period, including mainly beetles (Coleoptera) and flies (Diptera). In the late summer (end of August) aquatic organisms constituted less than 5% of the diet. Chironomids and mayflies (Ephemeroptera) dominated among autochthonous prey items, constituting ca. 3% and 1%, respectively. Allochthonous prey items constituted over 95% of the diet, ants being decidedly dominant (ca. 84% of prey items, with 100% frequency). PARASITES e helminth fauna of the brown trout from Mały Staw was poor and little diverse. 41 of the examined specimens contained a total of 2342 parasites representing only two species: a fluke Crepidostomum farionis (Müller, 1780) (Digenea), and a hookworm Neoechinorhynchus rutili (Müller, 1780) (Acanthocephala). e prevalence of infection was very high (97.5%) whereas the intensity of invasion ranged from 1 to 381 parasites per host (mean 57.1, S.D. 79.32). DISCUSSION A comparison with data on the growth of the brown trout from other high mountain streams and lakes shows that the growth of the species in Mały Staw is moderate (Tab. 4). At the same time its life span there is long a maximum of seven years. e condition coefficients are very low and practically only females before spawning exceed the mean value of one. A comparison with the populations of the species from lower altitudes in the mountains reveals that the values are among the lowest of those noted for the brown trout (KRAJEWSKI 1986). According to this author in the streams of Kotlina Kłodzka the Fulton coefficient for the species is on an average 1.24 1.41. e low condition in the studied population, expressed as the length/mass ratio (Fig. 4), is associated with the very scanty food resources of the lake. is is also confirmed by the appearance of the trout from Mały Staw, which represent typical starvation forms, with a large head and very thin, narrow body (Fig. 5). According to recent limnological studies (VRBA et al. 2008) Mały Staw is an oligotrophic, shallow, unstratified lake. Its phytoplankton includes only 14 taxa of algae, its zooplankton consists of 10 taxa. Such a poor food basis results in the role of autochthonous organisms in the trout s diet being limited to the late autumn. In the summer, a significant role in the diet is played by allochthonous organisms. e trout food composition during the occurrence of ice cover was not studied. It should be expected, however, that like in the Tatra lakes (DAWIDOWICZ & GLIWICZ 1983, GLIWICZ 1963), besides benthic organisms, an important role may be played by planktonic crustaceans. An indirect confirmation is provided by differences in the species composition between the lakes Wielki Staw and Mały Staw. According to VRBA et al. (2008) in the fish-free Wielki Staw both cladocerans Daphnia pulex and copepods Cyclops abyssorum are present, while copepods, but not Daphnia pulex, are found in Mały Staw. An analogous situation is observed 156

in the Tatra lakes (GLIWICZ & ROWAN 1984). In Wielki Staw in the valley Dolina Pięciu Stawów Polskich, where there is no fish fauna, both cladocerans and copepods are present. In Przedni Staw, stocked with brook trout Salvelinus fontinalis in the second half of the 20 th century, only Cyclops abyssorum tatricus occurred. In conditions of poor food basis the trout quickly removes large and conspicuous cladocerans. C. abyssorum is also consumed by the trout, especially just before the ice cover disappears, when mature females of the crustacean have large, conspicuous egg sacs, but the eggs of the species can develop also a er passage through the trout s alimentary tract (GLIWICZ & ROWAN 1984). Checking if the situation in Mały Staw is the same would require examination of trout caught during the period of occurrence of ice cover. Fig. 4. Dependence between length (Tl in mm) and weight (in g) of the brown trout (S. trutta m. fario) from Mały Staw Ryc. 4. Zależność między długością (Tl w mm) i masą (w g) pstrąga potokowego (S. trutta m. fario) z Małego Stawu Only two parasite species were found in the examined trout Crepidostomum farionis and Neoechinorhynchus rutili. C. farionis is a common intestinal parasite of salmonids, and the brown trout is regarded as its typical host. Both the prevalence and the intensity of infection with this parasite (87.8%; range: 1 139, mean: 20.2) are very high. Compared to the data of ŚLUSARSKI (1958 a,b,c): prevalence 27.6 48%, and more recent results of ROKICKI et al. (1998): prevalence 21.5%, intensity 8 22% for S. trutta m. fario, Salvelinus fontinalis, rainbow trout Oncorhynchus mykiss from the Tatra National Park (TNP), the trout from Mały Staw displays the highest indices of invasion with this parasite. e values exceed also those obtained in the National Park of Góry Stołowe: 14.8% and 1 4, respectively (POPIOłEK et al. 2004). e other recorded species (N. rutili) is a parasite of alimentary tract of several dozen fish species of various families, including salmonids. is parasite also shows very high indices of invasion in the studied trout population (prevalence: 85.3%; range: 1 369; mean 45), much higher than those reported by ROKICKI et al. (1998) 51.1% and 1 54 and ŚLUSARSKI (1958b) 11.3 14.0% from TNP. Such high values of these indices, combined with the extremely low species richness of the parasite fauna, seem to be characteristic for the locality. e considerable altitude and the harsh climatic and hydrological conditions limit the occurrence of a rich fauna of aquatic invertebrates (VRBA et al. 2008). is is clearly confirmed by our own and other authors (GLIWICZ 1963, GLIWICZ & ROWAN 1984, JARA et al. 1972) studies on feeding of the brown trout in oligotrophic montane lakes. Since aquatic invertebrates are intermediate hosts for many endoparasites, their low 157

diversity may explain the poverty of the trout parasite fauna. Furthermore, limited possibilities of fish migration from this mono-species lake result in a cumulation of the parasites occurring there, and consequently a mass invasion and permanent infection of the fish. e two-species set of parasites in trout from high mountain oligotrophic lakes is by no means a new observation. A similar situation was observed by DYK (1956, 1957) in three lakes in the Slovak part of the High Tatras. Tab. 4. Growth (in mm Tl) of the brown trout (S. trutta m. fario) in selected high mountain Sudetic and Carpathian streams and lakes (data of other authors were re-calculated on Tl, according to KRAJEWSKI 1986) Wzrost (w mm Tl) pstrąga potokowego (S. trutta m. fario) w wybranych wysokogórskich, górskich potokach oraz jeziorach Sudetów i Karpat (dane innych autorów przeliczono na Tl, wg KRAJEWSKI 1986) River-lake / Author(s) Age / Wiek Rzeka-jezioro / Autor(zy) I II III IV V VI Mały Staw (lake) (present study ) 83.8 143.0 180.3 229.0 270.9 293.0 Czerwona Woda (KUSZNIERZ et al. 2006) 62.4 118.7 165.6 247.6 - - Dańczówka (KUSZNIERZ et al. 2006) 79.6 135.0 161.8 - - - Morawka (KRAJEWSKI 1986) 85.9 134.3 173.0 214.2 - - Srebrnik (BłACHUTA & ZACHARCZYK 2000) 88.0 143.0 183.0 - - - Grządzki Potok (BłACHUTA & ZACHARCZYK 2000) 68.0 106.0 149.0 175.0 - - Jedlica (BłACHUTA & ZACHARCZYK 2000) 60.0 102.0 135.0 168.0 191.0 250.0 Łomnica (BłACHUTA & ZACHARCZYK 2000) 90.0 160.0 197.0 - - - Divoka Orlice (LOHNISKÝ 1963) 66.0 130.9 176.0 215.6 - - Rokytenka (LOHNISKÝ 1963) 64.9 121.1 167.2 179.3 224.4 - Moravica (HOCHMAN 1957) 97.9 163.9 223.3 272.8 - - Rybi Potok (ŻARNECKI & BIENIARZ 1967) 110.0 199.1 260.1 322.3 - - Białka Tatrzańska (SOLEWSKI 1965) 97.3 141.9 190.8 - - - Jelešna (HOLčIK & BASTL 1969) 93.5 154.0 202.0 - - - Bela Orava (HOLčIK & BASTL 1969) 80.3 142.9 218.9 233.2 - - Bely Vah (KIRKA 1969) 77.0 132.0 188.1 236.6 - - Černy Vah (KIRKA 1969) 75.9 130.9 187.0 217.8 - - Maly Poprad (KIRKA 1969) 83.6 130.9 180.4 242.0 - - Poprad (lake) (KIRKA 1964) 69.3 106.7 134.2 157.3 - - 158

Fig. 5. Brown trout (S. trutta m. fario) from Mały Staw (photo A. Witkowski) Ryc. 5. Pstrągi potokowe (S. trutta m. fario) z Małego Stawu (fot. A. Witkowski) SUMMARY An ichthyological survey carried out in 2004 2005 in the KNP included lakes and streams. Forty five individuals of the brown trout (Salmo trutta m. fario L.) were caught in three periods in Mały Staw. e material provided the basis to estimate the growth, fecundity, food basis and parasite fauna of the fish. e brown trout in the montane oligotrophic lake grows with a moderate rate, reaching in consecutive years the sizes: I 83.8, II 143.0, III 180.3, IV 229.0, V 270.9, VI 293.0 mm Tl. Its condition was poor, the condition coefficient rarely exceeded value 1. Studies on feeding of the brown trout in Mały Staw showed that the autochthonous food resources were very poor. In the studied population at the beginning of summer and in the late autumn small prey items, mainly chironomids, constituted the bulk of food. e best feeding conditions for the trout in the lake occured in the summer when the fish feed on large organisms, mainly allochthonous insects which constitute over 95% prey items. e helminth fauna of the trout from Mały Staw was composed of two species: Crepidostomum farionis (Müller, 1780) representing Digenea, and Neoechinorhynchus rutili (Müller, 1780), a member of Acanthocephala. e general prevalence of infection was very high (97.5%), the intensity ranging from 1 to 381 parasites per host (mean 57.1). 159

POLISH SUMMARY W latach 2004 2005 w Małym Stawie (Karkonoski Park Narodowy) w trzech okresach (16.11.2004, 17.06.2005 i 31.08.2005) złowiono 45 pstrągów potokowych (Salmo trutta m. fario L.). Materiały te posłużyły do oceny tempa wzrostu, płodności, pokarmu oraz ich parazytofauny. Pstrąg potokowy w tym górskim jeziorze rośnie przeciętnie, osiągając w kolejnych latach rozmiary: I 83.8, II 143.0, III 180.3, IV 229.0, V 270.9, VI 293.0 mm Tl. Jego kondycja jest niska, bowiem współczynnik kondycji rzadko przekracza wartość 1. Badania nad odżywianiem się pstrągów potokowych w Małym Stawie wykazały, że autochtoniczna baza pokarmowa jest tam bardzo uboga. U badanej populacji na początku lata i późną jesienią trzon pokarmu stanowią małe ofiary, głównie Chironomidae. Najlepsze warunki pokarmowe w tym jeziorze pstrąg ma w okresie letnim, gdy odżywia się dużymi organizmami, głównie allochtonicznymi owadami, których udział przekracza 95 %. Helmintofauna pstrągów Małego Stawu jest mało zróżnicowana. Odnotowano 2 gatunki pasożytów: Crepidostomum farionis (Müller, 1780) reprezentującego Digenea, oraz Neoechinorhynchus rutili (Müller, 1780) należącego do Acanthocephala. Ogólna prewalencja zarażenia była bardzo wysoka i wyniosła 97,5 %, podczas gdy intensywność inwazji wahała się od 1 do 381 pasożytów w jednym osobniku żywicielskim, średnio 57,1. Acknowledgements We are grateful to Andrzej Raj, PhD, Director of the Park, for the logistic help provided by the staff of the Park and for issuing permits to catch the specimens; we thank Mr. Mariusz Kleszcz, M.Sc. (Polish Angling Association Wrocław District) for carrying out the net catches. e authors thank two referees Dr. M. Čech (Institute of Hydrobiology, Czech Republic) and Dr. A. Štrojsová (Krkonoše National Park, Vrchlabi) for their helpful comments on an earlier dra of this manuscript. REFERENCES BłACHUTA J. & ZACHARCZYK K. 2000: Pstrąg i lipień. Oficyna Wydawnicza Multico, Warszawa, 206 str. DAWIDOWICZ P. & GLIWICZ Z.M. 1983: Food of brook charr in extreme oligotrophic conditions of an alpine lake. Environmental Biology of Fishes 8: 55 60. DYK V. 1956: Parasitofauna ryb tatranských ples. Československá Parasitologie 3: 33 42. DYK V. 1957: Dynamika endoparasitů ryb tatranských jezer. Biologia 12: 333 351. GLIWICZ Z.M. 1963: Wpływ zarybienia na biocenozy jezior tatrzańskich. Chrońmy Przyrodę Ojczystą 19: 27 35. GLIWICZ Z.M. & ROWAN M.G. 1984: Survival of Cyclops abyssorum tatrcicus (Copepoda, Crustacea) in alpine lakes stocked with planktivorous fish. Limnology and Oceanography 29: 1290 1299. GLOGER C.L. 1833: Fische. In: Schlesiens Wirbelthierfauna. Breslau 70 76 pp. HOCHMAN L. 1957: Ichtyologický výzkum řeky Moravice. Sbornik VŠZL v Brně 1: 83 117. HOLčIK J. & BASTL I. 1969: Notes on the biology and origin of trout Salmo trutta m. lacustris Linnaeus, 1758, in the Orava valley reservoir (Northern Slovakia). Zoologické Listy 18: 381 402. JARA Z. & MARKIEWICZ F. 1968: Zdrowotność ryb w stawach Tatrzańskiego Parku Narodowego w roku 1967. Wszechświat 7 8: 175 177. JARA Z., MARKIEWICZ F. & BORY-MIąCZYńSKI T. 1972: Results of investigations on the state of health of the trout in lakes of the Tatra National Park in years 1966 1970. Acta Hydrobiologica 14: 129 141. KIRKA A. 1964: Vek a rast pstruha potočného (Salmo trutta m. fario) v pramennej oblasti rieky Poprad. Zoologické Listy 13: 221 228. 160

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